Who's responsible?

Belgian media outlets published a security camera photo of three men they said police suspect are behind the bombings. The picture shows three men with dark hair, pushing luggage carts in the airport. Their identities are unknown.

Authorities blamed suicide bombers for the attacks, but began a manhunt for at least one suspected surviving attacker Tuesday.

The Islamic State group took credit for all three explosions Tuesday, according to SITE, a U.S.-based intelligence organization that monitors terrorist activity online.

There were three explosions

Two explosions occurred during morning rush hour Tuesday at the airport in Zaventem and one at a downtown metro station near European Union buildings. Belgium's federal prosecutor confirmed the blasts were terrorist attacks. Authorities raised Belgium's terror threat to its maximum level. The Islamic State has claimed responsibility for the terror attacks, according to SITE Intelligence Group.

Death, injury toll is rising

The Belgian government confirmed 34 dead in the attacks. Belgium's federal health minister, Maggie De Block, said the explosions at the airport killed 11 people and injured 81. Brussels Mayor Yvan Majeur put the subway death toll at 20, with more than 100 injured there.

President Obama addresses attacks from Cuba

President Obama addressed the Brussels attacks Tuesday morning at the beginning of his long-awaited speech to the Cuban people at the National Theater of Havana.

“We will do whatever is necessary to support our friend and ally Belgium in bringing justice to those who are responsible,” Obama said.

He said the world must stand united “regardless of nationality, or race, or faith, in fighting against the scourge of terrorism.”

Travel information

Officials said Brussels Airport will remain closed at least through Wednesday. The airport, which serves at least 24 million people each year, is located about 7 miles northeast of central Brussels. The airport is tweeting additional information @BrusselsAirport. By late Tuesday, some Brussels' train stations began reopening.

Security ramps up in New York, D.C., Chicago

U.S. Attorney General Loretta Lynch was briefed on the Brussels attacks early Tuesday and was coordinating how the FBI and other federal law enforcement agencies could provide assistance to Brussels authorities. The New York Police Department, meanwhile, was ramping up security at major transportation centers, similar to actions taken following the assaults in Paris. Security was also tightened in Washington, D.C., and Chicago. There were no indications of specific threats against U.S. targets, authorities said.

Witness describes the scene

In this AFP/Newslook video, a witness describes the scene at the Brussels airport: "I heard an explosion, that was the first bomb ... when we came out of the elevator, from that moment, the second bomb exploded and then we saw doors flying ... ceiling coming down, smoke on everything."

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A witness recalls seeing "doors flying" after the blasts at the airport. Video provided by AFP
Newslook

Incident follows the arrest of the Paris terror suspect

Salah Abdeslam, the main fugitive from November's Paris terror attack, was arrested Friday along with two other suspects in a raid on an apartment in a Brussels suburb. A federal law enforcement official, who is not authorized to comment publicly, said that based on the coordinated nature of the attacks it was likely that the assaults had been long planned but were accelerated following last week’s arrest.

Protesters clash with riot police after a peaceful gathering was disrupted by right-wing demonstrators in Brussels. The demonstration in the Place de la Bourse is believed to be in reaction to last week's terrorist attacks in Brussels and was later dispersed by riot police using water cannons. Sylvain Lefevre, Getty Images

People wait inside a sport complex turned into a crisis facility for passengers in transit following the evacuation of Brussels Airport, on March 23, 2016, in Leuven, Belgium. Sophie Kip, AFP/Getty Images

People gather to leave tributes at the Place de la Bourse following attacks on March 22, 2016, in Brussels. At least 31 people are thought to have been killed after Brussels Airport and a subway station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. Carl Court, Getty Images

Rescue teams evacuate wounded people outside the Maelbeek metro station in Brussels on March 22, 2016, after a blast rocked at the station, located near European Union institutions. Belgian firefighters said at least 26 people had died after "enormous" blasts rocked Brussels Airport and a downtown metro station. Belgium raised its terror threat to the maximum level. AFP/Getty Images

Belgian police patrol the Warandepark (Parc de Bruxelles) near the Wetstraat (Rue de la Loi), which was evacuated after an explosion at the Maelbeek subway station in Brussels. Nicolas Maeterlinck, AFP/Getty Images

Belgian police officers and rescue workers gather on the Wetstraat (Rue de la Loi), which was evacuated after an explosion at the Maelbeek subway station in Brussels. Laurie Dieffembacq, AFP/Getty Images

An injured woman leaves the scene at Brussels Airport, after explosions rocked the facility in Zaventem, Belgium, on March 22, 2016. Authorities locked down the Belgian capital after the attacks. David Crunelle, AP

A picture provided by Twitter user @evanlamos shows passengers leaving a metro train between the Arts-Lois and Maelbeek metro stations after an explosion at Maelbeek station in Brussels. Evan Lamos, Euractiv, via European Pressphoto Agency

This video grab shows emergency rescue workers tending to an unidentified victim of an explosion at a metro station in Brussels on March 22, 2016. Explosions rocked the Brussels Airport and the subway system, just days after the main suspect in the November Paris attacks was arrested in the city, police said. AP

A victim receives first aid by rescuers, on March 22, 2016, near Maelbeek metro station in Brussels, after a blast at the station near European Union institutions caused dozens of deaths and hundreds of injuries. Emmanuel Dunand, AFP/Getty Images

A man lies wounded in Brussels Airport after explosions ripped through the departure hall. All flights were canceled, arriving planes were being diverted, and Belgium's terror alert level was raised to its maximum level, officials said. Ketevan Kardava, AP

Policemen stand guard near a security perimeter set in the Rue de la Loi near the Maalbeek subway station, in Brussels, on March 22, 2016, after an explosion. A string of explosions rocked Brussels Airport and a city metro station. Nicolas Maeterlinck, AFP/Getty Images

Windows are shattered at Brussels Airport in Zaventem after a two explosions targeted the main hall. A string of explosions rocked the airport and a city metro station today, as Belgium raised its terror threat to the maximum level. Jonas Roosens, AFP/Getty Images

#JeSuisBrussels messages flood social media

#JeSuisBruxelles and #JeSuisBrussels were trending on Twitter in a sign of solidarity with victims. The hashtag, which means "I am Brussels," was trending worldwide. Others used the hashtags #PrayforBelgum and #PrayForPeace to offer their condolences.